In vitro kinase activity assays and effect of the E528K mutation.
(A) Specific kinase activity of Abl83-534, E528K (orange), Abl83-534 (red), Abl83-519 (light blue), Abl83-517 (green), Abl83-515 (magenta), and Abl83-534•asciminib (asc, blue). (B) Bar plot of fitted Michaelis-Menten vmax values derived from the kinase assays in panel A. Numerical values are given in Table 1. (C) Detailed view of the E528-R479 salt bridge in the structure of the assembled Abl core (PDB 2FO0). Distances between the E528 carboxylate oxygens and the guanidinium sidechain hydrogen of R479 as well as the backbone amide hydrogen of E485 are displayed as dashed lines and indicated in Angstrom. (D) Superpositions of the 1H-15N TROSY resonances of V130, T136, and G149 for apo Abl83-534,wt (red), apo Abl83-534,E528K (orange), Abl83-534,wt•imatinib (blue), and Abl83-534,E528K•imatinib (magenta) showing the increased imatinib-induced core disassembly of the Abl83-534,E528K mutant.